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Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
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Ras binding opens c-Raf to expose the docking site for mitogen-activated protein kinase kinase

Kenta Terai1, Michiyuki Matsuda

  • 1Department of Tumor Virology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

EMBO Reports
|February 16, 2005
PubMed

Insights

Ras protein binding causes a conformational change in c-Raf, switching it to an active state. This Ras-induced change is essential for c-Raf to activate MEK signaling pathways.

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • Biochemistry

Background:

  • c-Raf is a key signaling molecule in the Ras pathway, located between Ras and MEK.
  • Understanding the Ras-to-MEK signal transduction mechanism is crucial for cell biology.

Purpose of the Study:

  • To investigate the mechanism of signal transduction from Ras to MEK.
  • To elucidate the role of c-Raf conformation in this signaling pathway.

Main Methods:

  • Utilized fluorescence resonance energy transfer (FRET) probes.
  • Studied the interaction and activation between Ras, c-Raf, and MEK.
  • Employed cytosolic and membrane-targeted Ras mutants.

Main Results:

  • c-Raf exists in two conformations: closed (inactive) and open (active).
  • Ras binding induces c-Raf to transition to its open, active conformation.
  • Ras binding is necessary for c-Raf to bind and phosphorylate MEK.
  • A cytosolic Ras mutant demonstrated that Ras-induced conformational change is critical for MEK activation.

Conclusions:

  • Ras binding induces a critical conformational change in c-Raf, enabling MEK activation.
  • This conformational switch is essential for effective signal transduction in the Ras-MEK pathway.

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